


Everything Changed

by Mixolydia



Series: 'Til Death Do Us Part [2]
Category: Undertale (Video Game)
Genre: Baby Papyrus, Backstory, Cave, Character Death, Chased underground, Childbirth, Dadster, Death, English, Fluff and Angst, Gaster - Freeform, Good W. D. Gaster, Grillby likes Gaster, Heartbreak, I like to write gaster as a sobbing mess, Labour, M/M, Mages, Minor Character Death, Onesided Grillster, Pre-Barrier, Pregnant Gaster, Skeleton Pregnancy (Undertale), Sobbing, Sobbing Gaster, Soul Bond, Soulmates, Tears, The humans declared war, Toddler Sans, Wordcount: 1.000-5.000, birth in a cave, but was too shy, details of childbirth, i broke my own heart writing this, idk why, labor, seven mages mention, the barrier (undertale)
Language: English
Status: Completed
Published: 2018-01-03
Updated: 2018-01-03
Packaged: 2019-02-27 19:07:18
Rating: Mature
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 3,040
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/13254741
Author URL: https://archiveofourown.org/users/Mixolydia/pseuds/Mixolydia
Summary: Gaster and his husband are due to have their second child any day now... but the humans are growing restless.





	Everything Changed

**Author's Note:**

> I broke my own heart writing this ;-; It's kind of a sequel to 'Labour in the Elevator'. Or a prequel? Idk. (Thank you for all the Kudos and Comments on that fic btw!)
> 
> I like to imagine Gill as being similar to Underswap Papyrus if he'd managed to get in the Royal Guard. Also his uniform is the dark royal purple. Gill's full name is Gill 'Sans' Corbel-Aster. (Gaster and Gill double-barrelled their surnames when they married, Gaster has always been known as Gaster though so they just kept calling him that.)
> 
> Bold is when they speak in Wingdings. There's only a few lines but still.
> 
> I have no beta so feel free to point out any errors.  
> \--------------------------------------------------------

The day started just like any other in Gaster’s home. Gaster was _trying,_ without much success, to feed his fussy son his breakfast. The boy was having none of it and was refusing to co-operate with his Papa.

“Sans, come on… you usually like eggs, don’t you?” Gaster sighed as he looked down towards his son.

The three year old toddler wasn’t having any of it and with a ‘hnnn!’ proceeded to grab the plate of eggs and tipped it over the side of his high chair, sending the contents crashing to the floor before Gaster could stop it from happening. He rubbed his forehead, the signs of a headache beginning to bloom in his skull as he looked down at the giggling toddler, poking him with a fork. He looked down at the mess on the floor and wondered just how he was supposed to clean that up. Just as he pulled out the dustpan and brush, he heard the tell-tale noises of his mate coming down the stairs. He smiled as he felt long, lanky fingers wrap around his own.

“Here, let me clean that up for you…”

Gaster smiled as the dustpan was removed from his grip and he turned around to face Gill, his mate and Sans’ father. He was dressed in his General’s uniform and looked rather impressive as a skeleton monster at 7 feet tall was apt to do. He was one of the Generals in the King’s army and a long-time friend of the royal family. He gently brought a hand up to cup Gaster’s head, tilting it so he could kiss him. He chuckled as Sans made ‘blurgh’ noises behind them.  He glanced down and gave Gaster’s swollen stomach a rub before letting him go and poking Sans in the nose, earning a giggle from the toddler.

“You, young man…” Gill said as he bent down to sweep the mess off the floor “need to behave for your Papa. He can’t move as well and I have a meeting  so… behave?”

Sans just burbled at him.

“Another meeting? Is it the humans again?” Gaster frowned.

Things had been tense between the humans and the monsters in recent years. The humans were convinced the monsters were trying to take over the land and currently blamed them for the plague that was ravaging human towns and villages as the plague seemed to have no effect on the monsters.

“Yeah…” Gill sighed as he dumped the contents of the dustpan in the bin. “The humans are getting angrier. I just hope our King can find a solution soon or things will start to really go downhill.”

Gaster shivered as Gill placed the dustpan down before wrapping his arms around Gaster best as he could. With the baby due any day he was worried that both Gaster and the baby would be in danger if things weren’t resolved soon. He gave Gaster a gentle squeeze and felt his soul shudder slightly as Gaster trembled in his arms. Gaster buried his face in Gill’s chest as he tried to blink away the tears that were forming. Gil simply rubbed soothing motions on Gaster’s back as he calmed down. There was a knock on the door and Gill pulled away from Gaster, giving the other a kiss on the top of his skull.

“That’ll be Amethyst coming to pick up me for the meeting… will you be ok?” Gill frowned.

“I’ll be fine... this meeting is important, you don’t want to miss it.”

Gill pulled Gaster back to him and kissed him. He smiled down at him. “Nothing is as important to me as you and Sans.”

Gaster smiled and wiped the tears from his face. He walked to the door as Gill was pulling on his shoes. A lavender furred bunny monster stood and saluted as the door opened.

“Corbel! Are you ready to go?” Amethyst practically yelled at him.

“Just about, Sable. Just give me one moment…” He fastened the laces on his boots and stood up. He turned to Gaster, kissing him again and smiling.

“Take it easy, love. Rest and you…” turning to look at Sans, who was still in his chair “Behave yourself, Sans.”

Sans just waved.

“Be safe, Gill…” Gaster whispered.

“I will. I love you.” Gill walked towards the door.

“Love you too.”

Gill smiled and gently shut the door behind him.

* * *

The great hall was alive with noises; mummers and chatter as monsters filed in. Gill slid into his seat, which was next to Amethyst. The queen was on the other side of her. Gill frowned as he could feel the tension in the air.

“Sable, what’s going on?” He whispered to the bunny.

“The humans are not happy right now, Corbel. There have been rumours that a monster has killed a human. Reports are coming in, but no-one seems to know anything.”

“That’s crazy, Sable! You know as well as I do that we don’t have the soul power to do such a thing!”

“We know that Corbel, but the humans are determined to latch on to anything that could put us in a bad light. Tensions are strained and something like this could very well…”

“Yes, but surely…”

“Shh.” The queen scolded as the King stood at the head of the table “It’s about to begin.”

* * *

 Gaster was giving Sans a bath, currently amusing the toddler with a rubber duck, when Gill burst through the door startling both Gaster and Sans; Sans started to cry and Gaster accidentally threw the duck at Gill on reflex where it hit him on the head.

“Gill!” Gaster scolded as he picked Sans up, attempting to soothe the boy. “What’s the meaning of this?”

“The humans…. have declared war on us, Gaster.”

“… _what?_ ”

Gill walked over and sat on the toilet seat. He reached out and picked the duck up, staring at it as he rubbed a hand over his face.

“They’ve accused the monsters of harboring a monster that absorbed a human soul. They said we were planning to wipe the humans out… The King tried to reason with them but failed…”

“But, but it would’ve been impossible for us to hi—“

“The humans have called upon the great mages.”

Gaster stumbled and almost fell into the bath. He put a hand on the ridge and sat down to steady himself.  He glanced at Gill who was _still_ staring at the duck. “…what.”

“They’ve called upon the seven great mages. The rumours were true, Gaster. They’re going to seal us underground. Humans have already killed monsters and the royals have already begun to herd the monsters still alive towards the mountain as a condition of surrender. Some humans don’t care though and are killing monsters as they go… we never stood a chance…”

“So, what…”

Gill finally looked up and at Gaster, who was holding his son and was carrying their unborn child.

“We have to pack and leave for the mountain at once.”

* * *

 A couple of hours and a full inventory later, Gill and Gaster left the place they’d called home for the past five years. Gaster had Sans in his arms as he looked sadly back at their home. This was where they’d built a life for themselves. The first time Gill carried him over the threshold as his husband. All of their children had been conceived here, the twins were buried near here. Hope had been born here when Gaster found out he was pregnant for the second time. Many memories had been made here and his eyes watered with the fact that they now had to leave it all behind. Gill slid up to Gaster’s side and wrapped an arm around him, giving him a gentle squeeze and leading him down the garden path.

They stepped out of the front gate and looked around the area. It seemed too quiet and the air was tense. There were no sounds of children playing, no-one in sight and even the birds weren’t singing. Sans squirmed in his Papa’s arms and Gaster shifted him in his arms. Gaster had an uneasy feeling in the pit of his stomach; he rubbed his head over Sans’ skull then over his bump in an attempt to settle the restless baby who was currently kicking at the walls of the womb. Gill led Gaster through the town, hand never far away from his sword and keeping his family right by his side.

His head whipped round as he could hear gunshots in the distance and could see smoke rising into the sky. He swallowed and pressed on.

* * *

 As the sun set, they were forced to stop for the night. Gaster started a small fire and fed Sans some of the food they’d packed. They were just over halfway to the mountain and, apart from a couple of bunny monsters in the distance, they had yet to see anyone else. Gill stared into the fire but didn’t want to worry Gaster any more than he had to.

Morning found them moving faster than they had yesterday as the sounds of gunshots and fighting seemed to appear closer to them with every passing hour. They were three quarters of the way there when they found themselves ambushed by humans brandishing swords.

Gill placed himself between Gaster and the humans, drawing his sword in warning. He growled as a human lunged forward and he had to dodge to the side to avoid his skull being cracked open. He struck out at the human’s legs but the human dodged out of the way and went for Gill again. Gill hissed as the sword made contact with his arm. He glanced around and saw the other humans closing in. He scowled and turned to Gaster.

 **“Run.”** He yelled.

Gaster blinked stupidly “…what?”

 **“Gaster!”** Gill hissed as he ducked again **“You need to run!”**

**“No! I can’t! I can’t leave you—“**

**“There’s too many of them!”** Gill lunged and made contact with a human’s side, causing blood to spill out. **“There’s too many of them! I can’t protect you from all of them!”**

Gaster went to step forward but stopped as Gill glanced at him. Gaster nodded slightly, turned and fled as fast as he could. **“Be safe.”**

Gill smiled, shook his head and stared at the humans “Alright. Who wants a piece of me?”

* * *

 Gaster ran as fast as a full term pregnant skeleton could… which was to say wasn’t very fast at all. He had to keep stopping to catch his breath and he couldn’t see where he was going very well. He leant against a tree for a moment as he attempted to catch his breath when he felt a stabbing pain in his side. A human had found him and had aimed for Gaster’s side.

“Hah… can’t let more creatures like you into the world.”

Gaster gasped as pain rippled throughout his body and with blind luck managed to throw magic at the human, who was sent flying and landed on the floor unconscious. Gaster glanced around for Sans as the boy had been dropped when Gaster was attacked. Gaster panicked when he couldn’t see his son anywhere. Fearing his son had been dusted, he cried out for him for there was no response. Gaster’s soul tightened in fear, then in pain as he suddenly felt a gush of liquid between his legs. The attack on him had triggered his labour.

He picked himself up from where he’d fallen to his knees and slowly walked towards the mountain, stopping every so often to breathe his way through the contractions.

* * *

Gaster found himself stumbling into a cave at the base of the mountain range. Light streamed in through holes in the ceiling as he struggled to move away from the cave entrance. The floor of the cave was slippery and he had liquid magic dripping down his legs. He had managed to stop the womb leaking out of the injury to his side and he just hoped the womb would hold out until the baby was born.

He eventually came to a stop, leaning on a large stalagmite. His breathing was shallow and his throat was thick with panic and tears. Purple tears rolled down his face, both with the thoughts of the family he may have lost and with the pain that was coursing through his body.

He gasped as a strong contraction washed over him and he realised what sort of situation he was in. He was stuck in a cave, alone and in labour. The contractions were getting stronger and closer together and there was no way of calling for help. He realised he was going to have to do this alone and his breathing became more erratic. He frantically pulled up his inventory and pulled out some towels he’d packed to lay on the floor. He cried out as another wave hit him and he collapsed onto the floor, his legs unable to support his weight. He pulled his legs up to his face as he let out a wail.

“I can’t… I can’t do this alone…” He cried to himself.

A particularly hard pain had Gaster gasping as he laid there and feeling the baby descend into his pelvis struck fear into his soul. This baby certainly wasn’t going to wait for Gaster to move. Sobbing quietly to himself, he managed to spread the towels he’d taken out on the cave floor. He managed, with a bit of a struggle, to remove everything from the waist down but kept his long coat on. He scooted over and sat on the towels as more pain racked his body.

He rested his back on the stalagmite and pulled his knees up, spreading his own legs as he panted through the next few contractions. Wiping his tears off his face, he bore down with the next contraction. The pain was indescribable and Gaster thought his soul was going to shatter from it, but finally he could feel the baby beginning to crown. With a cry, he pushed hard and the baby’s head popped free. Slumping back, he took a moment to breathe as the hardest part was over. He reached down and cradled the baby’s head in one and panted as the body slowly slid out of him. One final contraction saw him catch the baby with both hands as it slid completely out with a squelch.

He grabbed a spare towel and wrapped the baby in it, cradling the baby to his chest as the magic womb dissipated. He lay there for a moment as he caught his breath.

* * *

 Gaster had no idea how long he’d laid there with the baby, but stirred slightly when he heard familiar voices.

“…ast… Gast… Gaster! Can you hear me?”

He turned his head towards the cave entrance and was glad to see General Grillby and Amethyst heading towards him although he frowned when he noticed Amethyst was missing an arm and Gill wasn’t with them.

“…ver here.”

“Gaster? Oh god, Gaster!” Grillby ran over, face full of concern “What happened?”

“…humans… was running… attacked… waters broke. Gill… Gill held humans back… Told me to run… found cave…” Gaster sighed and lent into Grillby’s heat, he was cold from being in the cave. “…where’s Gill?”

Grillby flushed and looked away, unable to answer the question. Amethyst smiled sadly and couched down in front of Gaster, looking at the baby who was beginning to fuss. “What’s the baby’s name?”

“The baby…? It’s a boy, so… Gill wanted to call him Papyrus.” He frowned “Where… where is he? Where’s my husband?”

“…” Grillby sighed. “…He… Gill pointed us in your general direction… We found him, on the ground. He’d been wounded… he told us to look after you, before he… Gaster… Gill’s… he’s fallen.”

“….What?”

Grillby pulled out the red scarf Gill had always worn with his uniform. “He… was fatally wounded. When we found him, he was fighting a human. Between us, we finished the human off… but Amethyst lost her arm and Gill lost his life… I’m sorry.”

“No… he.. he can’t be… he…” Gaster was in shock and his eyes filled with tears. Amethyst simply took Papyrus and cradled him in her one good arm as Gaster took the cape.

Grillby held Gaster has he realised what that pain in his soul was, even after the birth. It was the pain of the soul link he and Gill shared severing as the other had fallen. Grillby held the skeleton as he sobbed his eyes out, face buried in Gill’s scarf. It was only a couple of days ago that he’d told him he loved him. He told Gill to be safe! The labour he’d gone through felt like nothing compared to the heart break of losing his soul mate. Grillby rubbed his back and didn’t even flinch as he felt the tears seeping through his clothes. He’d known the couple for a long time and felt incredibly sad for Gaster’s loss. Eventually, after what seemed an age, Gaster cried himself to sleep.

Grillby shifted slightly, standing and picking Gaster up, with Gaster’s head tucked against his chest. Amethyst led the way out of the cave, Papyrus asleep in her arm and they slowly made their way around the mountain and eventually joining the flow of monsters heading into the mountain proper. The new queen was standing at the mouth of the entrance, making sure the monsters made it through and she gasped in concern as she spotted Grillby with the Gaster in his arms. Grillby shook his head and headed in. Sans gasped as he spotted his Papa, Sans himself making it into the mountain under the watchful eye of Undyne’s family after being found unconscious under a bush.

Grillby laid Gaster down on one of the unoccupied makeshift beds and placed a blanket over him. Amethyst placed Papyrus in one of the Moses baskets her cousin had kindly donated before leaving the tent. Sans waddled over and gazed into the basket, admiring his new baby brother. Grillby sat down and sat on the stool by the bed, watching over Gaster and held his hand; ensuring that there would be a friendly face there when he woke up.

**Author's Note:**

> PS: Another thing I had (which ties into this loosely) is that Sans was the firstborn... Papyrus was the _fourth._


End file.
